Ryan is the first and tbh probably last natural born supe. He is the ONLY natural born super being in the Boys universe. And unless they retcon it down the line, it's a fact
Other supes who have the same abilities as their parents who are also supes, aren't natural born supes, and if you're like "yeah but they have the same powers", there's clearly an obvious answer to that. Genetics & DNA. Now I'm not expert, I'm pretty shit at science, but Compound V effects everyone differently, it gives them different powers, because of how they're built Genetically, because of how their DNA is, cause it's unique, but someone's child, will have the same DNA. Andre & Maverick have the same powers simply because they share very similar and strong Genetic ties to their fathers, so they're DNA is gonna be similar, but very clearly, they don't have the EXACT same power set, just very similar, they're parents injected them with V as children, I mean hell maybe they didn't do it, maybe Vought did it without them knowing to get a more likely chance of another powerful/potentially popular supe, due to Genetics
Ryan is the first natural born supe because his father is not the same as every other supe. Homelander wasn't born and then later injected with V, he was created using the the combo of sperm from another very powerful supe, and compound V, he was created in a test tube, he wasn't birthed, he was manufactured in a lab. So V, is a part of Homelander, it's not only in his veins, it's just him, it's one of the things that made him. "If Homelander is the only supe capable of naturally producing another supe, then why did they use Soldier Boy's sperm?", that can be answered by what I said above, Genetics. Both Soldier Boy & Stormfront were pretty powerful supes, especially probably THE most powerful before Homelander, and they're also different from other supes, they got the premium OG Comp-V, ones made by Frederick Vought himself, AND because they were adults when they received it, and Soldier Boy was hands down the strongest supe before Homelander, so clearly they struck gold with him, so why wouldn't they use his clearly superior DNA, even if the V didn't do anything to his sperm to produce a natural supe, it's still pretty good DNA.
So Homelander is as powerful as he is because he was made using Comp-V, and the DNA of someone who has the best V+Genes combo ever. So he was able to create Ryan. And also, to anyone who says "but how can Translucent & Polarity have kids if supes are supposed to be sterile?", well, it's never said supes are sterile, it's just that Vogelbaum and the others involved in his creation/upbringing thought he was sterile, they didn't think he could produce offspring, and they told Homelander they didn't think he could, Homelander says "I didn't I co-".
Hope that clears it up