You can only download/reinstall the current versions of available Apps. If you have deleted Apps from an older model iPad, it may not be possible to re-install the Apps that you have deleted.
If your iPad cannot be updated to a more recent version of iOS/iPadOS, sufficient to meet the minimum requirements of the available Apps that you are attempting to install, you have no alternative other than to replace your iPad with a much newer or current model iPad.
The tags appended to your post suggest that you have an iPad mini. Given that Apps that you have listed require iPadOS 14, 15 and 15.1, this implies that you have an iPad mini1, mini2 or mini3.
Whether or not you are able to update your iPad to a newer version of iOS/iPadOS will be dictated by the iPad model - and the currently installed version of iOS. You can find this information here:
Settings > General > About
Not sure which iPad you have? Identify your iPad model.
For information, here is a list of the highest version of iOS supported by the older models of iPad (for simplicity - “generations” are shortened to a number) that are restricted in their ability to be updated:
32-bit devices (obsolete)
iPad1 - iOS 5.1.1
iPad2, iPad3 and iPad mini1 - iOS 9.3.5 (WiFi Only models), iOS 9.3.6 (WiFi+Cellular)
iPad4 - iOS 10.3.3 (WiFi Only), iOS 10.3.4 (WiFi+Cellular)
64-bit devices
iPad Air1*, iPad mini2 and iPad mini3* - iOS 12.5.7
iPad Air2, iPad mini4 - iPadOS 15.8.3
iPad5, iPad Pro (9.7"/12.9" 1st generation)* - iPadOS 16.7.10
iPad6, iPad Pro (10.5"/12.9" 2nd generation) - iPadOS 17.7.5
(*) obsolete
Newer models are all able to be updated to the current version - iPadOS 18.3.1
- iPad Pro 13" (M4)
- iPad Pro 12.9" (3rd generation and later)
- iPad Pro 11" (1st generation and later + M4)
- iPad Air (3rd generation and later + M2)
- iPad (7th generation and later)
- iPad mini (5th generation and later + A17 Pro)