Actually what I do is download the SVG of undraw.co and then pull up something like https://boxy-svg.com
The guy who said it's called Art School is a douche.
Once you start editing the SVG it's just like anything else, heck go and mix and match a bunch of undraws and you can defintiely create what you want.
I didn't "make" the eagle. I just took an SVG of an Austrian coat of arms from Wikimedia Commons and edited it using Boxy SVG Editor, an online app. The rest I created using internet assets and Paint 3D.
Well let's address the elephant in the room immediately: mouse and keyboard is terrible tool to draw, and you'd better off sticking with traditional media if that's the only tools available to you right now.
Now, I'm not saying it's impossible, I know some people can create amazing things with mouse but they're exceptions rather than the rules.
So if you're still determined to create clean artwork with these limitations, I suggest you use vector-based drawing software instead. Keep in mind though that your workflow would be vastly different than regular drawing. The best free, easy-to-use vector drawing tool I can think of right now is https://boxy-svg.com which is browser-based so you don't even need to install anything.