Thats right, Manuel Neuer is only in the team because he played so many years for bayern münchen and they respect him so much, a valuable act from the club. But they have to get someone now and De Gea i find interesting too, like you. He is currently also approached by clubs from saudi arabia and if they offer him a lot more money, bayern münchen will not succeed. So they have to look at many goalkeepers. I think Kepa Arrizabalaga is also a good option, recently fc chelsea got another goalie and Arrizabalaga not the number 1, this will make him angry.
Manuel Neuer is a representative of the country in football and he is an important player in the national team as a captain and vice versa at the club because that's why he is highly respected and becomes one of the important players at the club. But talking about competition in the league, Bayern Munich also needs a goalkeeper who has above average abilities and can at least match Manuel Neuer a little, the goal is to complete the team when the league starts again in the next few weeks.
De Gea is attractive and has almost the same abilities as Manuel Neuer even though the characteristics and playing styles of the two are different. I prefer De Gea's abilities compared to Arrizabalaga because maybe Bayern Munich just need a short-term option for an interim goalkeeper.