can you explain the timelines a bit? i mean why is a alpha timeline is "alpha", why does the doomed ones exist and why are there no alternate timelines that arent doomed

The timeline that births a new universe is the alpha. The doomed timelines exist to piece together the alpha timeline in some way or another. For example the timeline that Davesprite came from was doomed but in the end it was always meant to happen because he came back and became Davesprite. Another example is all the doomed timelines the trolls had which were all doomed but in the end were necessary because they needed all the Aradiabots to help them defeat the BK.