More specifically, I think the part that seems copied is at 2:13 of the original[2], as it leads into a solo-ish bit which in the AI version sounds similar still, but goes on to do its own thing:
The only things they have in common are vibes (in the contemporary sense, not vibraphones). Two dudes singing about sex in falsetto at 120bpm over prototypical R&B/funk elements isn't special. If that's the bar for copyright infringement then 99% of the popular music canon is illegally-derivative. Marvin Gaye was a singular talent but that doesn't mean that his heirs should be able to collect money every time somebody plays an electric piano bassline and sings about making whoopie in alto II.
1) They had a musician come in and deconstruct the songs, and she showed that many of Blurred Lines elements copied the “rhythm” and “feel” of the sheet music, not the master recording.
2) Robin Thicke said in an interview he told Pharrell they should make something with the groove of Got To Give It Up.
As a non-musical person in a jury, those points are convincing enough that there was intent to copy the song even if the final song is clearly different. Though, it should never have been down to a jury and judge to decide.
Even more hilarious, a couple of years ago the Gayes tried to sue Pharrell because of an interview where he mentioned again Got To Give It Up was inspiration for Blurred Lines. Luckily that failed, but they definitely have it in for Pharrell it seems.