If the sources of your inspiration are in the public domain your creations based on them are original art and not fan art, since there is no copyrighted material in your new creation.
You can still choose to call it fan art if you want, but if you choose not to, that's fine as well, since it's in the public domain it can be used by anyone freely.
Notice this though, this only applies to how we see fan art within deviantART. This does not apply to other websites nor is it legal advice of any sort. We just help you categorize your works on deviantART.
Also, remember to make sure what material you use in your creations, if you decide to draw the original Alice in Wonderland or based on it (which is public domain) but you use Disney's Alice in wonderland character designs or other materials from the Disney interpretation of Alice, that would be fan art. Disney's Alice in wonderland is copyrighted even if the original Alice in Wonderland is in public domain.