Even then JKR wrote HP to still possibly include Nevil as a/the Chosen One which is why his parents were tortured then murdered because said Chosen One was meant to be born around a specific time and both Harry and Nevil applied. While Harry carries the lion's [heh] share of the burden Nevil does later on play a significant part in destroying the big bad by pulling off a Crowning Moment of Awesome [pulling the Gryffendor sword out the Sorting Hat] and killing/destroying the final Horcrux.

Neither the books or the films made any allusions Harry wasn't the protag though despite the importance Nevil might play nor when he did play that role.