iCloud Photos have wrong date/time after download?

Hi-

Now that Google Photos has gone paid, I've just subscribed to iCloud Storage and am learning about all the wondrous and lovely features of iCloud Storage and iCloud Photos.

I take notes on my iPad, then once a month/term/whatever I download them and sort them into projects, weeks, classes, whatever. I do this based on the timestamp and datestamp. It's easy.

I just downloaded my notes for the last few weeks via iCloud.com and find that all of my notes, photos, screen captures, everything occurred at the moment I downloaded them, and not over the course of last month.

That is, all the dates and times are set to the instant they were downloaded, and not when they were taken.

How best can I sort them into days and subjects if I don't have access to the date & time they were taken?

Thanks for anyone who can provide assistance. I find this so weird, but It's probably user error.