Here's a couple of graphs I've found recently showcasing the attacking talents of Aguero and Jesus. The general gist is that Aguero is a bit better at scoring, and Jesus is a bit better at assisting. But their overall contributions are practically identical if you combine the two.
Interestingly, Jesus is getting more assists than he should, but he's scoring fewer than he should. He really should be level with Aguero, but as we know Jesus can be a bit shaky with his finishing [Personally I think his issue is confidence as opposed to ability]. They're both pretty equal it seems at getting into goalscoring positions, something they both do excellently.
I don't think this has been Aguero's best season for obvious reasons; his stats would probably be better going back (his undoubted quality is still apparent though). But Jesus is obviously getting older and in theory more game time, so his stats should in theory improve. I want to say here it's remarkable how good Aguero's output is despite his physical issues as of the last few years.
The takeaway is that Jesus isn't as of now as good a goalscorer as Aguero (how many are though?) but the team is unaffected with him in the team goalwise. As he gets older, if his finishing and creating improve, which they should with increased experience and game time, then it's highly likely we'll have a striker with a world class output. The worst case scenario fitness permitting is that he'd be our version of Firmino, and that's the worst case. Jesus will almost certainly not replace Aguero, but there's a chance he'll bring things to the table Aguero never had to make up for it.
We do need a third central forward option though, even if it isn't an out and out striker. Not only can we not rely on both Aguero and Jesus to stay fit for a full season but it'd give licence to possibly use both together or one of them elsewhere (eg Jesus on the wing). Plus it'd mean we can make the extra steps to protect Aguero's fitness, he's still an amazing striker who's undoubtedly better when he's not injured!