Be careful about comparing your artwork to other artists, especially professional artists you look up to.
It's alright to analyze and understand what you could do better next time but the "why doesn't my work look as good as theirs" is a very dangerous way of thinking. As if starting out wasn't hard enough...don't add to that by draining your confidence.

A long time ago I used to compare my artwork with artists I loved, usually digital artwork because it's so popular but that wasn't even a fair comparison. It's mentally exhausting and I can only blame myself for it. I would make myself depressed thinking I'll never be as good as them...literally a pointless draining cycle.

Have fun with your art. Focus on yourself and learn from your own work. Don't worry about how long it's taking to improve...draw because you enjoy it~