I don't have complete lists at hand, but a quick look at all-athletics.com's list, which goes to 1:02:00, and Association of Road Racing Statisticians' list (arrs.net), which goes to 1:02:16 shows no Indiana-born/HS athletes that I can identify on either. So, Bizuneh's is probably the fastest.
(Ditto for Yoder-Begley -- I don't think any faster than her were/are from Indiana high school backgrounds.)
ps. re Bob Kennedy -- no 1/2 marathons listed on any of his profiles; and in any case, he graduated from HS in Ohio.