I recently got a Carmona Bonsicle (which is what I like to call it) since my old Ficus Bonsai left us after 4 years and moving twice.
Anyways it had some fallout as it was expected after buying it in a store for just 15 bucks and the fallout slowed down but I realized some leaves turning black at the tops.
Now that might be because I watered it a little too much and the roots didn't get enough oxygen.
I try keeping it humid in my room by putting a wet towel onto my radiator but I myself didn't notice any difference.
I also have a growlamp which I turn on every other day as there ain't too much light 'cause of winter here in Austria.
But after inspecting it closely (because of the black leaves) I just found some insects on my Bonsicle. I guess it's because it ain't humid enough in here but I'm open to any other suggestions as I really want it to survive.
Please help me!

These are aphids. Treat with any regular insecticide. Some people have good results with spraying a soap/alcohol in water mixture. (A spoon of each to a litre of water)

Thank you! I'll try right away.

Aphids are also notorious for producing a sugary substance called honeydew (it's the excretion they produce after sucking the lifeblood from your plant), which attracts both ants and fungi.
Another thing I found reasonably effective when I had an infestation on my tomatoes was to spray them with neem oil extract (make sure it's not the concentrate), and in between sprayings squish the little buggers myself. The neem oil has the added benefit of being fungicidal, which was really important in the humid environment I lived in at the time.