FWIW, everybody is young. On ever message board I go to (and I go to a lot), I see "we're really young", but honestly, while some teams are a LITTLE younger than others, every single team has more underclassmen than upperclassmen.
1) Covid redshirt year means everybody is back a year
2) Redshirts
3) Portal attrition
4) Regular attrition.
There are ALWAYS more freshman and sophomores than juniors and seniors, and this is especially true with covid (think Jeff Sims being a freshman).
To wit, I looked at the following rosters (source: CBS Sports, because it's easy to format into a spreadsheet): at your schedule.
GT has 97/124 (78%) Freshmen and Sophomore:
NU: 98/114 (86%)
KSU: 71/105 (67%)
Clemson: 88/130 (68%)
UNC: 75/112 (67%)
Pitt: 74/125 (59%)
Duke: 67/114 (59%)
UVA: 77/126 ( 61%)
VT: 94/126 (75%)
Miami: 83/110 (75%) (only 9 seniors!)
BC: 64/114 (56%)
ND: 72/112 (64%)
UGA: 90/132 (68%)
As you see, you guys are on they younger end, but you're not outside the "normal range"
Further, probably the 2 worst teams on your schedule are the 2 oldest (Duke and BC).
I don't know that I buy "we're young" very much.