Inkscape provides also export of images as combination of LaTeX-Code for the text and PDF or EPS for the graphics. But you should use an up-to-date inkscape for it, because there were some versions with completely broken PDF-TeX export, where the generated TeX file contained
\includegraphics
commands for pages, which were not part of the exported PDF file.However, IMHO the main problem of the OP was to generate vector graphics from bitmap images. Indeed something inkscape can also do at least for such easy images. However, generating such images with TikZ directly shouldn't be a real problem as already told and shown years ago.