WWE had plenty of choices with the 2020 Royal Rumble. They had 29 other people to choose from. The company did originally have different plans for their Rumble winners, but they went with Drew McIntyre and Charlotte Flair as well.
The Wrestling Observer Newsletter noted that the original plan for the Men’s Royal Rumble wouldn’t have seen much change at all. McIntyre was always supposed to eliminate Brock Lesnar, but he wasn’t going to win.
The final two people in the match were Roman Reigns and Drew McIntyre anyway. McIntyre eliminating Lesnar was initially supposed to be enough to secure a WrestleMania match between Drew and Brock. Letting McIntyre win the entire thing further secured him a top spot at Mania.
The idea is that once he eliminated Lesnar, that McIntyre didn’t need to win, and that Reigns could win and challenge Wyatt so you have the two title matches as someone even.
In the end, WWE went with the idea to give Drew McIntyre both the Brock Lesnar elimination and the entire Royal Rumble win. That certainly turned out for the best when it comes to his overall push to the top of the roster.