This sounds like you don't know what the fuck your hiring for.
If you want juniors to fill out your team, why are you getting a bunch of seniors?
I can take multiple types of people, I'm casting a wide net to find value.
No, it sounds like there are clear differences in abilities.
If you think every junior/senior/staff has the same ability, you're delusional. Two people can broadly fall into the same bucket but be very different in terms of output.
100% wrong.
If I'm building a team, I don't need everyone at the exact same level. I want a mix. I want some juniors, some seniors and a tech lead. The job description is the same, I'm not writing 3 or 4.