UPDATE: Big thank you to all those who gave me advice! It led me to believe that there was nothing really wrong with my new tire, rather with my method of putting the tire on. There was no need to return the tire and exchange it for a smaller one - I used a "trick" of putting only half of the tire on the rim, then inserting the inner tube, then putting the other half of the tire on, and it worked! Now all is good :)
My old tire has worn out after a couple of years of use, and I decided to replace it. Unfortunately, the exact same model of the old Kenda tire is no longer for sale. So, I went to the local bike shop and bought a Schwalbe Land Cruiser tire of exactly the same size (42-622). However, when I tried to put the new tire on, it felt far too loose on the wheel.
My question is, have I bought the correct tire for my bicycle? Should I still be able to fit the new tire on my wheel? I don't know how to explain this in proper terminology, but it seems like my two tires are still very different, despite having the same ETRTO code. Attached is the image of my old tire on the right, and the new one (which didn't fit) on the left.