I can't download anything in my old iPads

Your iPad2 and iPad mini1 devices are obsolete - and have no trade-in value with Apple. Apple will, however, responsibly recycle them for free.

Your three iPad devices can only be updated to iOS 9.3.5 (WiFi Only models) or iOS 9.3.6 (WiFi & Cellular models).

Apple ended update support for iPad2 in September 2016. They cannot be updated to iOS 10 or later major versions of iOS as the internal hardware does not meet the minimum technical requirements for new versions of iOS/iPadOS.

Compatible Apps for your iPad are increasingly difficult to find - as third-party developers are increasingly dropping support for older versions of iOS preceding iOS11/12/13, which may severely limit their usefulness and utility. As such, if you want or need to access most current Apps, requiring more recent versions of iOS, you’ll need to consider replacement of your iPad with a newer or current model.

Of current models, even the entry-level iPad8 has specifications and capabilities that will massively outperform you current iPad - and is compatible with the vast majority of current Apps. Other models are more powerful still.

I hope this information provides helpful and succinct clarity as to your available options - and the limitations of your current iPad devices.

Apple may offer a trade-in discount, though this is less likely of the devices are very old. You cold try selling them on eBay, though again if they are very old they may only be worth anything for parts for repairs. Don't expect to realise more than a fraction of the original cost.

A1396 = iPad 2nd Generation (wifi+cellular)

A1455 = iPad Mini 1st Generation (Wifi+Cellular)

A1432 = iPad Mini 1st Generation (Wifi Only).

Since those devices are really old, I suggest that you make an appointment at an Apple Store and show them. They will judge if your devices still have some value, or they can be recycled only.

Regards

Giulio