In the new screenshot I provided, I circled the buttons I used that made a form which autogenerated fields based on the fields in my list on sharepoint. The screenshot also includes the DefaultSelectedItems properties as well as the Items code for the combobox in the user field. The Default property for the User card is ThisItem.User. As for the different codes I have tried, I have tried a lot since I've been working on this form the last 2 days and that would be a lot to list here.
I'm not sure why the app autogenerates the form to where the User section uses a combobox to find a specific user. I tried changing it to a regular text box for users to type in their name, but I couldn't figure out how to make that work.
I tried using a gallery like you suggested but that was not working at all.
The goal I have for this form is to have the user enter their name, which will autogenerate other fields on the form such as their email, ID, etc.