The insect is hard to see but could be an aphid in the winged phase or a fungus gnat. The black blobs do look like excrement but not from either of those. Check for caterpillars.

Ahh! I thought it might be the dreaded fungus gnat! I haven't seen any caterpillars in the soil and the leaves don't look like they're eaten. Is there any "natural" insecticide I could use on my plant/in the soil to kill whatever is in it?

I use organic neem oil mixed with castile soap to spray my plants and that gets rid of bugs like aphids, gnats and whiteflies plus thrips. You have to get the concentration right though. I spray my entire yard cuz I have a huge garden and mix a teaspoon of soap with 50ml of the neem oil and mix it all up in 15 litres of water in one of those huge backpack sprayer thingies. I'm thinking a good concentration for you would be a few drops of soap and like a teaspoon of neem oil then top up your spray bottle with clean water.

Try that out. The poop looks like caterpillar poop to me so you should examine your pots for them. As for the insect, it;s not really clear but that looks like a thrip to me. The neem solution should get rid of it.

Good luck!