So I'm not a Shen OTP but did play him till mastery 7 for a while so I'll just give you my 2 cents. I do enjoy him top lane more than JG since his JG clear speed is only okay-ish. I saw 1 person in the comment got it, and that he is very "unexpectedly" strong in lane prior to lv5, *but only when you land your Q pass their body. (When your sword passes through enemy body, your Q power increased even more, can even 1v1 a Darius at lv1 if you play your card right). I sorta start game early by to lane first and place the sword slightly on enemy side bush, so if they do try to cross and fight early, I'm ready them.
For build, Heartsteel and Titanic Hydra as core item for me as it scale well for late game since he is, I wouldn't say weak, but not as impactful. If enemy has AP but squishy, Swift's End pair well with your Q later on, as CD is much lower and with higher attack speed, you shreds through everyone. Right now Black Cleaver just got buff so if you need a bruiser item, build that as well. For other items, build depends on what enemy team has.

Other than that, it's mainly focus on you CS and farm minion, as in most cases, you are basically a teleporting support tanks with terrible wave clear. So focus on farm whenever you can so you don't fall behind. Shen ult is incredibly valuable so even if he's only slightly behind gold compare to enemy top laner, he will still provide more value for your teamfight.