I still remeber playing the very first Metroid on NES. I actually played it a lot but it was a love-hate relationship. It is the game with the most ridiculous password system ever! When you finally have entered the lengtly password, you will realise that all your energy tanks are empty and your curent health is very low. On top of it, the rockets empty too - so you have to grind everytime for a looong time before you can continue (at least in the later parts of the game). The game in it's originial form is basically unplayable today. Even with modern saving possibilities at Nintendo Online, the game is just not fun to play anymore.
Super Metroid on the other hand = one of the best games ever made! A cult classic that stands the test of time.
I only ever played those two Metroid games. I was interested in the Prime series but ended up never playing them. However, I definitely will buy Metroid Prime 4. To enjoy the game and its story, I don't think storywise you will need any knowledge of Prime 1-3. I will also plan to buy Metroid Dread (and even Metroid: Samus Returns on 3DS but hopefully they make a Switch port one day).