I think the way it makes sense is probably because the UK has been very quick off the draw in training Ukrainians and supplying weapons. And that speed helped blunt the Russian advance at the beginning, during the 48 hours when they thought they could take the whole country.
I understand the US is bigger and probably supplies more stuff and in the end will have more influence. But Biden has been more restrained, whereas Boris has been champing at the bit to supply planes, tanks etc. That would attract Putin's attention from his throne under the eye of Mordor.
It's not a competition. That's just what they said. We take it as a compliment! Who doesn't want to be Putin's number one enemy.
Glad your country is helping Ukraine too. It's Zelensky's show. Not America's. Or Britain's. They are the heroes.