Coloring out of the lines/interior of drawing

Hi everyone!

So, I drew a dinosaur-like creature sitting on a building. First, I drew it on paper and then placed it in Illustrator as a template. I went over it by using the curvature tool, but after a while started using the pencil tool for more accuracy and because it was easier to use in general. So, I now have a combination of curvature tool and pencil tool lines making up the dinosaur. However, when I select the whole dinosaur or just parts of it (e.g. the arms), the color goes out of the lines, it doesn't fit in the selection, which in this case would the interior of the dinosaur.

I tried thinking of any lines that haven't connected or any gaps inbetween them, but I couldn't solve it.

Is there anyone who could help me with this issue and tell me whether drawing with the pencil tool is wise when you want to fill color your illustration, since I am new to this program?

Also, is it okay to use both the curvature tool and pencil tool when drawing or tracing something?

Thank you in advance!

Cheers