I'll try my best to explain everything, as someone who has been using the oekaki boards for almost 7 years.
First of all, there is no shame in being in beginners. I was there for over 2 years, and while I was a bit bummed that all of my effort still couldn't get into intermediate, I kept pushing myself to keep drawing. Sometimes I thought it was crap, other times I thought it was perfect, either way I kept pushing to get better. Now i'm well in intermediate and I know I could be advanced if I put full effort into a piece. It took almost 7 years to get this far, it's something you have to slowly work on.
Onto the actual critique. The lines look kinda sketchy and a bit rigid in spots, they also get thicker in some odd areas(top of back, feathers, a bit on the back paws). I'd suggest using smoothing if you aren't, or upping the amount if you are. I use about 33% with my tablet, if you are using a mouse you may want to go even higher than that. Clean lines can really help give an art piece a more polished look. Coloring you did really good on, I don't see any uncolored spots or only a couple very minor places that it went over by like a pixel, which for the oekaki is an A+ job. I also want to say that I love the way you colored the spot markings, they're very cute! Going onto shading, it could use some work in placement. Shadows go away from the light source, and in your piece a clear light source is hard to find because the not all of the shadows seem to follow that rule. It can be a tricky thing to get the hang of, I still struggle with it a bit, but it again really helps give off a polished look.
Here are some tutorials to help show what I mean and to give examples of different kinds of lights. Also a lot of your drawing seem to use the burn and dodge tools to help with shading. They're fine in small amounts, but i've learned through the years that using a different layer with multiply or subtract for shading and add for highlights works out better. It also gives you the opportunity to tint the shadows/highlights, which can help make a piece pop. Onto anatomy. Since this is your own species I don't 100% know what the anatomy should look like, but you describe ft's as being close to foxes, so i'll go with that. The ears are very round and large for a typical fox, though I also get the impression thats just part of the character, pointing it out just in case. The hair is very round at the tips and it makes it look odd, i'd suggest making it pointier or styling it a bit differently, same with the cheek fur. The shoulder could go up a bit higher, and the back seems unnaturally bent. Quadruped animals do not bend the same way humans do, their backs are not able to bend like that, they have a gradual curve instead of a steep one. The back legs also look a bit long, and the hock(ankle part) shouldn't curve up like that. The partial line you have by the showing ankle would be a more ideal placement. The far back leg should be higher up, if you drew a line to connect it to the body you'd see its longer than the other one. The angle the ankle is at is also unnatural looking, i'd have it be closer the the type of angle on the other back leg. One other thing i'd like to point out is that foxes do not have hind dew claws, only front ones.
I'd suggest getting redlines done and using photo references(with proper permission and credit) to help improve your art skills. Another important thing is to just keep drawing. It took me years to get where I am, and I still have a lot to learn. Practice makes perfect definitely applies to art, just keep at it and you'll make it to intermediate.