It just isn’t possible, and we should want to dumb down the introduction too much. The Fediverse is not a centralised medium, and to participate in it, its users should understand that, analogous to how you would instruct people before using motor vehicles. Some things are just essential and need to be taught. Not teaching the stuff doesn’t make it disappear. If some people cannot get behind the idea, then either find novel, intuitive ways of conveying it, or just accept that they cannot be a part of the Fediverse.

Are you certain that Element does not run in the background? It always does for me, both on my Samsung with OneUI and on another Samsung with LineageOS. Perhaps not really helpful, but my observation is that Element’s background “listening for notifications” is quite reliable. Might this be due to some settings in your OS?