You might be right...initially I thought both looked a little big, but it's hard to tell without much context. The flea beetles I get are fairly small, but easy to see with the naked eye, and all black with smaller heads, but when I googled pictures of flea beetles I found some that look at lot like that.
On second thought I don't think the other one is an aphid. Body shape is a little off, it's probably too big, doesn't have the translucent look, and the antennae are pointing forward instead of backwards. I've been googling insects for a little while and I'm stumped, I can't find anything that looks like it.
On the other hand, I was able to identify an insect I've been finding on a lot of my plants. Fortunately these nasty looking things are beneficial insects.
I thought they looked like predatory insects, so I've been leaving them alone. Assassin bug:
Requiescat in Pace. Also been finding a ton of lightning bugs on my plants, apparently the larvae eat slugs.