I really should. I've been curious on looking into homology too. That the jordan curve theorem needs so much machinery intrigues me; I'd love to be able to understand its proof
Where I will think of homeomorphisms and linear transformations and such as not being instantaneous. I.e. not just immediately expanding x4 in the case of the matrix $4I$, but instead doing it in a smooth motion.
In particular, if we're cutting out holes, each hole removed reduces the characteristic by $1$ since that's one less face in the triangulation (but same # of edges and vertices)