How to merge stuff together?

I made this thing to test a 3D printer I have access to currently. I figured I would need to somehow merge it all into one big shape. I tried searching for a solution online but ended up getting more confused. Is there a method to just fuse the stuff together? Or do I have to do it manually?

Edit: I know about Ctrl+J, but that just seems to make it all one mess, with no respect to overlapping meshes.

Use ctrl+j and then do a voxel remesh to get rid of overlapping geometry.

Thanks! But what’s this voxel remesh you’re talking about?

It is in object data properties.

Found it, and it worked! Okay, there are a few splots where the teeth overlap the lips, but once it prints, I can just blame it on the printer. Thanks for the help!