I feel like outlines could be great on this guy. I might think that because it seems a little unfinished to me, like it lacks a shade or two or something. Steps away from your minimalist style but what if you snazzed it up a little, gave it some graphical flair, simple border and stuff, this way the complete avatar set could all have unifying design traits https://i.imgur.com/T1MlK9y.png
Thank you for giving me so many suggestions.
In terms of color, the three colors are indeed a bit less. It is more difficult to express snakes characterized by patterns with only three colors, and the effect is not satisfactory. I will try to include the background color in the drawing of the snake.
As for the boundary, I hope to fill in the name of the snake, but I have no specific ideas yet.