Basically the title, what made the lion so important to these people and why was it included in English, Scottish, or Danish flags when Europe has no lions.
https://www.reddit.com/r/AskHistorians/comments/9y7vio/how_come_old_coat_of_arms_such_as_normandys_have/
https://www.reddit.com/r/AskHistorians/comments/aua7i4/even_though_the_lion_is_not_an_animal_native_to/
https://www.reddit.com/r/AskHistorians/comments/cevrbe/why_did_lions_feature_in_european_symbolism_in/
One of these threads may answer your question.
Why did lions feature in European symbolism in the middle ages? How did most normal people even know what a lion was?
Even though the lion is not an animal native to England, it’s seen as a national animal of England. What is the history of the lion as a symbol in English culture? Who decided that this strange beast from a far off land should represent England?