I went to enclosed shelters decades ago because of similar concerns about snakes and other possible visitors.

During my tarp days I had mice run over my face, mountain beavers hop over my sleeping bag and slugs crawl onto my face as I slept.

I sleep much better knowing that I am fully enclosed in a tent. And for larger visitors I at least know that they must get through the nylon before their paws and teeth start on me.

In some cases I think the tent may discourage animals. A friend of mine recently discouraged an agressive dog, for example, by placing the opaque canopy of an umbrella between her and the dog.

I also recommend bringing most things into the tent. I left my empty backpack outside one night and some animal tore it badly because (I'm guessing) of the salty taste from my sweat.......and a friend of mine found a small rattle snake in her boot when she left it outside the tent.