Element uses Groups to animate separate objects with the correlating effect panel settings. There are 5 groups you can separately animate, however, within each singular group there are also Auxiliary Channels to animate the object without being in a separate group.
Group Folders allow you to have multiple objects within the same Group number. When you select two objects they will be put in a Group Folder by default. To take a model out of the Group Folder simply drag an object out of the folder.
Auxiliary Channels allow you to animate separate objects within a Group Folder. Click on an object and under the Auxiliary Animation change the Aux Channel dropdown to 1-10.
Then in the AE effect panel you can animate the object with the Aux Channel settings.
Another way to separately animate an object is to put it on a different Group number. Pull it out of the Group Folder and click on the dropdown to change the 1 to a different number.
Then in the AE effect panel you can use that Group number’s Particle Replicator options to animate that object.