Help! I’ve deleted some very precious photos

Go to iCloud.com and sign in with your Apple ID. It's certainly worth checking to see if they could be there. I doubt they will be as iCloud is a syncing service. When you delete frome one device, you delete from all. But check anyway.

It might also be worth noting that if you were using iCloud Photos on your old phone (which you must have been), those photos are actually not included in the iPhone backup.

What does iCloud back up? - Apple Support

So hopefully they are in the recently deleted area, otherwise they might be gone gone

Delete photos on your iPhone, iPad, and iPod touch - Apple Support

I'm terribly sorry to hear that.. here is some misc reading you can do to be prepared for next time

Set up and use iCloud Photos - Apple Support

iCloud Deconstructed - Apple Community

If all you have for Apple devices is your iPhone, you may not even want/need to use iCloud photos. It's better for syncing than anything else. (ie you also have an iPad and a MacBook and you want the pictures readily available on all devices). Also can be used to free up space on your iPhone.

So if you would prefer to keep your photos on your iPhone and make it so that your backups do include the photos, you'd want to turn off the switch in Settings > [your name] > iCloud > Photos.

If you take a bunch of photos and you don't have a large capacity phone, you will eventually run out of space, but there are options. You can look into Google Photos, which I hear actually keeps the photos and lets you delete them from your device. Amazon photos might do the same thing. I'm sure there are other options as well.

You could also transfer photos to a computer and delete from your phone to save space

Transfer photos and videos from your iPhone, iPad, or iPod touch - Apple Support

If you do continue to use iCloud photos, and you come into the same situation.. Next time turn off iCloud photos on the old phone before deleting the pictures. This should have prevented what happened to you.

Also, just in case this info is helpful to you.. if you are planning to leave your iPhone as is and let your son use it, you should really be creating him an Apple ID and wiping the phone, setting up family sharing.. possible parental controls. Apple IDs were not meant to be shared. A few support articles to review below

Help your child set up an iPhone, iPad, or iPod touch - Apple Support

How to create a new Apple ID - Apple Support

Set up Family Sharing - Apple Support

Use parental controls on your child's iPhone, iPad, and iPod touch - Apple Support

Try going to icloud.com , sometimes if you have the right setting turned on it will have uploaded to icloud. You can view the icloud photos saved on this site right in photos which will apear immediately after you sign in. If its not there you will probably have to check and make sure its saved somewhere else or otherwise I cannot help.

You have learned a very important lesson about the necessity for a good working backup. Important photos and data should be backed up to your computer or an external drive. I don't even trust one backup. I have back-ups of my back-ups. I learned the hard way, too!

It does it because you had it signed it was problaby signed in on the other phone when you deleted it.

Deleted means gone forever. That's why we make a backup first.

As I already told you, go to iCloud.com and sign in with your Apple ID and Password. Check the photo section.

there should be an area in the Photos app in iCloud that says 'Recently Deleted'