[SalesForce] How to use Ids of the test data factory records in test class

Created a DataFactory class to reuse the code in test classes. I am not able to get the List of users record id into the test class. Can anyone please help me with this?

It is currently throwing Error : Initial term of field expression must be a concrete SObject: List

TestDataFactory Apex class:

@isTest
public class testDataFactory{
    public Static List<User> cuser(){

        List<User> UsersList = new List<User>();

        Profile p = [SELECT Id FROM Profile WHERE Name='Profile1'];
        User usr1 = new User(Alias = 'aa', Email='testuser111@testorg.com',
        EmailEncodingKey='UTF-8', FirstName='yhsl',LastName='test', LanguageLocaleKey='en_US',
        LocaleSidKey='en_US', ProfileId = p.Id,
        TimeZoneSidKey='America/Los_Angeles', UserName='testuser111@testorg.com');
        UsersList.add(usr1);
        User usr2 = new User(Alias = 'ab', Email='testuser1112@testorg.com',
        EmailEncodingKey='UTF-8', FirstName='iuqwet',LastName='Test', LanguageLocaleKey='en_US',
        LocaleSidKey='en_US', ProfileId = p.Id,
        TimeZoneSidKey='America/Los_Angeles', UserName='testuser1112@testorg.com');
        UsersList.add(usr2);
        insert UsersList;
        return UsersList;
    }

}

Test Class:

@isTest
private class TestClass
{
    Account Acc = new Account(Name='Test');
    Insert Acc;
    Acc.ownerId = testDataFactory.cuser().UsersList[0].id; // It is throwing Error : Initial term of field expression must be a concrete SObject: List<User>
    update Acc; 
}