Yeah,in the beginning, it's normal to be weak. Weak to strong. This is one of the main themse of most shonen anime. So yeah, it will start with Boruto as a genin, working his way up.

Deidara can be killed by poison. He can be killed in an ambush. He can be killed with genjutsu. He is not unkillable. Anyone that is not a god can be killed. Naruto himself was almost killed from 1 simple scratch of Sasuke's poisoned kunai.

All you need is imagination to set the stage. If you're gonna pit a scrub like Sai in a head on fight against Deidara, yes, he will use. But that is not how assassination works. Assassinations happen when the target least expects it or is at a disadvantage.

As for saying that everyone that is not Naruto or Sasuke are irrelevant, does it mean that you are irrelevant because you're not Bill Gates? Your life doesn't matter?

Or just because Mike Tyson was the champion, none of the other fighters mattered?

Just because Police are not as strong as Seals, are they irrelevant?

Your logic is incredible. I'll just drop it, you seem to lack common sense.