I think that the reason that Oliver didn't bring back E-1 Laurel when he died because if he would've brought her back, then the new team that he assembles season 5 doesn't exist, therefore changing the past.
I do not think so. If it was this way bringing back Moira Queen would probably change the timeline so that Thea wouldn’t have gone to Corto Maltese and that would result in Thea not knowing Oliver’s secret. But as we see in the finale she know who Oliver is
I think it was because there couldn’t be two Laurels on one Earth. Just look at what happened to Beth. In order to bring back Earth 1 Laurel, he would have had to kill Earth 2 Laurel, and he wasn’t willing to do that.
There's probably a variety of reasons that he didn't bring her back. In my honest opinion, we should've gotten a much better explanation than we got in the Arrow series finale. The explanation of "There was nothing about [Earth-2 Laurel] that needed to be fixed" was incredibly vague and just didn't make any sense.
I honestly think that everyone except the paragons shouldve had Earth-Prime versions of themselves made... because according to the Earth-Prime timeline the multiverse never existed... so how would there be an E-2 Laurel?