I think the answer to this question (with emphasis on "all") is clearly none that we know of. Plastic is really hundreds of different polymers, each with different priperties and uses.

If a new material can take the place of some of those, that's a win. We don't need to replace plastic wholesale with a single new thing, there's no rule against using multiple targeted materials, we've just got used to material science being all about one material for recent history.

There are many uses of plastic that can be easily replaced with cornstarch, bamboo, or leaves. Food packaging can be with aluminum or glass, granted those last thousands of years too but the point is they’re more easily recyclable and we can make a circular economy around them.

Those don't work in Tokyo during summers. 40C/104F ambient temp, all-day 100% RH, optional salt in the wind, the every populated areas of the country is basically a bioreactor. We just haven't found such materials that can make distinction between just waiting at a crosswalk in Tokyo and being in a bacterial composting chamber.

I mean, the simplest solution to this problem might be to leave that borderline uninhabitable hellhole and move to Europe where food in bamboo wraps or home-washed glass containers don't start stringing in matters of hours, but that's not an option for most.

Also, you might be thinking that some of those wrap materials were historically viable, but it has to be noted that the content inside were much less healthier than it is now. Medieval Japanese people were estimated to have taken as much as 50g/day/person of salt, which is literally 10x WHO recommendations, or like 1.5 cups per week, or one small backpack worth per year. Adding that much of salt to food is no different from marinading it in chemical preservatives, only much worse.