You can also use the little volunteer as a watering aid for either the basil or capsicum, which both like it dry. If the volunteer wilts before the others do (it likely will) you can wait to water until you see evidence of it wilting. I often allow volunteers to remain in my containers of plants that prefer a dry soil (pines, junipers, etc.) for just that purpose. Al

The first one may be Ipomoea cordatotriloba. The second appears to be a Solanum, possibly S. americanum. Pokeweed is the next one, Phytolacca americana. The last is an Amaranthus. Here is a link that might be useful:

looks like some kind of tree seedling

It looks a lot like the Campanula Rapunculoides that I have in one concrete bounded area. It is a prolific seeder, as well as spreading by the roots - if I didn't keep it deadheaded, and it weren't confined by the concrete, it would be all over. I keep it because it is pretty and blooms all season, but it isn't something that I recommend to anyone else. It is considered a noxious invasive in many areas. Information Get rid of it now I would say! ETA: I overlooked that you already have identified creeping bellflower, but this new one still shares the characteristics: purple stem at the base, sideways running root, heart shaped leaves with stems in the early growth. Really does look like mine!