Thanks Khan  for your help, but I still can not get it to work.
I'm starting as a programmer I'm still crawling.
I will inform the code below with the comments to see if you can help me.
Basically, what I need is that for each alert found and passed to it, its alert (Alert1__c), its id (Name), CSS settings (Warning, Error, Success, etc) and a button to close it .
I do not know if my code is a bit confusing, but if you can help me, I'll be very grateful.

Controller.js 



({


   doInit : function(component, event, helper)
    {

  var action = component.get( "c.getMsgs" );

         action.setCallback(this, function(response) 
                           {                               
                             
                               var state = response.getState();

                               if(state == 'SUCCESS')
                               {                                   
                                   var alertMsgList = response.getReturnValue();
                                   var lista = [ ];                                  
                                   
                                   
                                   if(alertMsgList.length > 0)
                                   {                                       
                                       component.set("v.showToast", true);                             
                                   }
                                 
                                   
                                   
                                   for(var i = 0; i < alertMsgList.length; i ++) 
                                   {                                       
                                       var alerta = alertMsgList[ i ].Alerta1__c;
                                       var tipo = alertMsgList[ i ].Tipo_de_Alerta__c;
                                       var titulo = alertMsgList[ i ].Name;                                       
                                       
                                       // Stores all the alert records found in the database
                                      lista.push(alertMsgList[i]);

      						       }
                                   
                                   // sends to the <aura:attribute name="html" type="List" /> the list of retrieved alerts

                                   component.set("v.html",lista);
                                 
                                    //  var tipoAlerta = component.find( "alerta" );
                                   
                                   // I need to configure each alert according to its type, according to its id
                                   var tipoAlerta = document.getElementById("!v.Alert.Name");
                              
                               //This is the CSS configuration that will be sent to each alert, however it needs to check the type of alert, it is in the registry (if Warning, sucess, error, etc). I believe that it would have to be inside the for                                 
                                              $A.util.addClass( tipoAlerta, "slds-notify" );
                                              $A.util.addClass( tipoAlerta, "slds-notify_toast" );  
                                              $A.util.addClass( tipoAlerta, "slds-theme_success" );  
   
                                   
     }
                               
               
                          else {
                                   console.log("Failed with state: " + state);
                               }
                           }); 
        
        
        $A.enqueueAction(action);
        
  
        
    },

   
    //THIS FUNCTION HIDE ALERT BY ID - I believe that it would have to be inside the for
   close: function(cmp, event, helper) 
    {
 //   $A.util.addClass(cmp.find('alerta'), "slds-hide");
        $A.util.addClass(document.getElementById('{!v.lista.Name}'), "slds-hide");
    },
   
   
       
    
})

Alert.cmp





<aura:component implements="flexipage:availableForRecordHome,force:hasRecordId,lightning:actionOverride,lightning:backgroundUtilityItem" access="GLOBAL" controller="AlertController">   

    
<aura:attribute name="html" type="List" />
    
    
<aura:attribute name="showToast" type="boolean" default="false"/>
    
<aura:attribute name="Alert" type="Alert__c" default="{'sobjectType': 'Alert__c',
                         'Tipo_de_Alerta__c': '',
                         'Name': '',
                         'Alerta1__c': ''
                          }"/>
    
    
<aura:handler name="init" value="{!this}" action="{!c.doInit}"/>
    
    
<aura:if isTrue="{!v.showToast}">
    
           <aura:iteration items="{!v.html}" var="lista">        
					<div class="demo-only" style="height: 4rem;">
		
   							 <div class="slds-notify_container slds-is-relative">    
				
        							<!--<div aura:id="alerta" role="status">  -->
                                 
                                 <div id="{!Lista.Name}" role="status">  
													<div  class="slds-notify__content">
                            
                                                                <h2 class="slds-text-heading_small ">                
                                                                     <aura:unescapedHtml value="{!lista.Alerta1__c}" />  
                                                                </h2>
                            
                                                    <lightning:buttonIcon iconName="utility:close" variant="bare" alternativeText="Close"
                                                     iconClass="{!v.type == 'warning' ? 'light' : 'dark'}" size="small"
                                                     class="slds-button slds-button_icon slds-notify__close slds-button_icon-inverse"
                                                     onclick="{!c.close}"/>      
    
													</div>
									</div>
							</div>
					</div>
			</aura:iteration>
    
    
    
    
   

</aura:if>
    
    
    
</aura:component>