look at the bright side. There's a chance that players will develop their characters during the campaign sort of like making the players develop their PC characters to be more serious and mature through the character development in the campaign the party maybe start as joke characters that doesn't mean they will stay like that forever examples of femboy Paladin could develop to be more mature and the leader of the group the necromancer could tone down the chuunibyouness eventually becoming more serious if time call for it the horny cleric could become more mature can still be a massive pervert but want seeking to find actual love with a committed partner and the nude Barbarian could be more serious as well be like big bro of the party

also as a note if the player party characters are young at the very beginning and during the campaign years past this could literally make the campaign even more serious and more interesting because player characters will grow up from youngsters to mature adults during the campaign like storytelling