There are some nice things going on here. I like the color choices. The main thing I'd change would be to have every sprite use the same pixel size. There's a pretty wild mix of resolutions going on here, which causes all kinds of artifacting and clashing. Those seams that are showing up in the wall near the character in the first picture wouldn't happen the same way if everything was drawn to a fixed-resolution canvas at 1x before being scaled up for presentation. (There might still be a gap there, but the fix would be more obvious - it'd either be 1 full pixel or not be there are all.)
A more minor point on the character sprite: The line right near the waist where tunic meets legplates has a boundary of two colors that are extremely similar. I think it would read better if the dark gray and dark maroon had more contrast between each other, either with some sort of boundary line or just choosing different color values that are more different in brightness.
Keep practicing! This is a good start. If you're writing a game with these graphics, it might be fun to start a
devlog. Also, we'd love to see you
introduce yourself in the dedicated thread for it!