(1) create static documents in the simplest and most standard lossless (as far as possible) format.
(2) store them on a durable enough, yet simple enough medium. Today that would probably be something simple like an USB stick.
(3) transfer to new medium periodically, and take the opportunity to convert obsolete media files to new formats, if needed (you could keep the originals and each 'generation' as historical reference).
(4) train your children, grandchildren, etc to perform (3) and perhaps to rewrite the instruction in their own words (to cater for technology and language changes)
This also allows for multiple copies for easy backups and to entrust to each descendant individually.
wrt (2), I remember reading (watching? maybe it was a YouTube video), that the answer to long-term storage is optical media. There was even a brand of discs that advertised itself as being a 300-year data storage medium.
The engineer in me wants to make some sort of metal etched disk medium to store data on and bury it somewhere with a marker on top. Preferably with instructions on how to retrieve the data.
That may be the answer for the durability of the medium but, I think, it is a red herring for the scenario described here and loses sight of crucial aspects:
(1) The data must be easily retrievable. Any custom solution will be too expensive to produce then read, and so will be any solution that does not evolve over time. It's already not simple to read a 40 year old obsolete medium...
(2) Once the data have been retrieved they must also be easily interpreted. I have no idea how easily it will be to interpret a 500 year old data format. For instance, anything can display a JPEG file today, but what about in 500, let alone 100 years? JPEG did not exist only 30 years ago, MP4 was released 20 years ago this year. This is a blip compared to 500 years.
So if the aim is archaeological and the intended recipients are a bunch of future PhDs in well-funded universities then maybe. But if they aim is to have the data readily available for an average person then both the medium and the data format must evolve over time and the most standard medium is probably the best choice for each technological generation. Even the instructions and the language they are written in must evolve over time.
You do need to hope that your descendants will keep at it over time.
You might be better off with some kind of ceramic, to ensure that the storage medium isn't more valuable as a recycled material than for its information content. Ancient Sumerians had the right idea.
(1) create static documents in the simplest and most standard lossless (as far as possible) format.
(2) store them on a durable enough, yet simple enough medium. Today that would probably be something simple like an USB stick.
(3) transfer to new medium periodically, and take the opportunity to convert obsolete media files to new formats, if needed (you could keep the originals and each 'generation' as historical reference).
(4) train your children, grandchildren, etc to perform (3) and perhaps to rewrite the instruction in their own words (to cater for technology and language changes)
This also allows for multiple copies for easy backups and to entrust to each descendant individually.