I don't know why people are comparing hojlund to Rooney. Look at similar players over the past 20 years even, so that is technical and big forwards. Off the top of my head and some googling to see if they were of similar enough heights/remember some names:
- Ibrahimovic
- Lewandowski
- Džeko
- Cavani
- Giroud
- Kane
- Berbatov
- Drogba
- Mario Gomez
- Ruud
- Etc
Literally none of these guys did anything before like 21 or 22. Take out the guys who don't actually have pace, or who aren't hold up play type of CFs and you are left with a tiny list. Most of them didn't even play in a bigger league or for a bigger club before 20/21. Guys like Dzeko and Lewandowski were at Teplice and Lech Poznan still.
We aren't talking about a smaller dynamic CF like Rooney or Mbappe who float around. We aren't talking about a guy who broke out early by just having extreme physical superiority from a young age and knowing how to use that physical superiority early like Haaland or Lukaku (yes Hojlund has good physical attributes, but his play style is much more focused on technical aspects from what I've seen and he's not yet fully taken advantage of or learned how to use his body unlike those guys). He's a type of CF which is a pretty rare breed, a rare mix of attributes but one that also takes a few years to get used to everything. But one every team would love to have. Complete, technical, bigger CF who can be a reference points but with pace and power. I'm not saying he'll turn into those guys, but it's not a surprise at all that he hasn't broken out super early (and he's only 20 anyway FFS) given his style, and his rapid rise over the past year suggests he is rapidly adapting and making a step up.