Disclaimer : I know it's very tough to compare anyone to the olympic champion, especially highschool athletes. Moreover, Jakob Ingebrigtsen had professional training since a very young age while they only started running seriously 3/4 years ago so obviously that is not a comparison. This comparison is in no way intended to belittle anyone, it's just for fun.
First of all, Jakob was born just after track season (september), while Leo and Lex were born before track season (february I think) so we are going to use the internation category system for the comparison, because that is what counts for international championships like world U20.
For example, Leo Lex and Aaron (2005) all still have two years left as U20s, while Colin Sahlman (2003) doesn't have any years left as an u20. That means Leo, Lex and Aaron can still run world juniors in 2024 and hopefully get some medals.
Jakob was born in 2000 :
17th year (2017) : 1:49:40 3:39 3:56 8:00 13:36
18th year (2018) : 3:31 3:52 13:17
19th year (2019) : 3:30 3:51 13:02
Aaron Sahlman was born in 2005 :
17th year (2022) : 1:48:91(-0.5s) 4:01(+5s) 8:01i (+1s)
Colin Sahlman was born in 2003 :
19th year (2022) : 1:48:07(-1.3s) 3:39(+9s) 3:56(+5s)
Lex Young was born in 2005 :
17th year (2022) : 4:01(+5s) 7:57i (-3s) 5000m 13:44(+8sec)
Leo Young got sick during track season so it's going to be tough to compare him to anyone. During XC season + the two track races he got to run(not including Arcadia), he almost always beat Lex, sometimes by several seconds (he beat him by 4 seconds in the mile and 4 seconds in the 3200 they ran early season). He even beat Colin once in XC. I'm going to make a conservative bet and assume he is only 1 second faster than Lex in the 3000m and 5000m, and that his 4:00 mile in march was the best he could have done (he clearly would have run faster since Aaron, Lex and Colin went on to cut several seconds off their mile times later in the season).
Leo Young was born in 2005 :
17th year (2022) : 4:00(+4s) 7:56 (-4s) 13:43(+7s)
Colin Sahlman is slower everywhere than 2019 Jakob but can't blame him since he's only a highschooler and Jakob was a pro runner for Nike travelling all over the world in 2019.
Now if we look at the 3 younger guys, they are surprisingly close to 2017 Jakob, with the young twins running fairly close to Jakob over longer distances, while Aaron is literally faster than him in the 800m. All three are surely world class for their age (u18s) and I really think a huge part of it is due to having Colin as a training partner, leading and pushing them in training, just like Jakob had his big brothers.
It's also interesting that according to Brosnan, Lex and Leo are on pace to match Jakob's 2018 5K time, we'll se how it goes but that would be a huge achievement, taking highschool running to another level. We should also note that Jakob only ran 3:58 on his first try in 2017 in may at Pre, being dragged the whole race, while Leo ran 4:00 on his first try in March, running more than a lap and a half alone, so Leo may be even closer to Jakob than we think.
All that to say, Newbury Park are really good and they actually hold their ground fairly well against the olympic champion, so no they really aren't four G-League runners or national class runners, they are all world class for their age.
Now does that mean anything ? I don't think so, there is a lot of speculation, it's just that I'm a bit of a running nerd and Jakob being my favorite runner I like to compare other runners with him.
My opinion is that long term : Aaron will be a 1500m specialist, Colin a 1500/5000m type just like Jakob, Leo a 5000m runner (a 4:00 mile on his first try, as a junior, shows a lot of speed) and Lex a 10000m specialist (a little more strength based, maybe like Nico).