Let me start by pointing out that, based on your description, your colleague is not incompetent and your colleague technically did not do anything wrong. Is it wrong to say "we did" for tasks given to your team as whole? No, because after all everything is team's effort. At the same time, it is also not wrong to say "I did" when it is indeed only your effort alone. It's just playing with words for one's own gains. Wh…
I didn't share everything that happened in two years time but just some vague summary. Is hard for someone that does nothing to do something wrong. In all the meetings we had his first thought was "let's find an open source alternative that does that for us" even in some highly customisable and domain specific solution that won't be available in GitHub for you to use. Or not any "how to do ...." search in Google can solve.
Yet, after more than two years, is still have lacks on how our infrastructure and the application works. And he still propose useless open source or SaaS solutions that don't fit at all our usecase because he doesn't even know what the applications do.