... How do you have a "Humble born" noble. Similarly, how do you have a royal consort that isn't involved with someone else. That is basically what consort means.
That first part isn’t so unusual, (I want to say especially in historical Asian cultures, but it was actually pretty widespread), if you don’t take the “humbly” part too literally. A family may have an illustrious lineage but have fallen on hard economic times, even to the point of actual poverty, while still being considered firmly in the “aristocratic” class.
It’s a totally different genre and feeling, but the current series *I Want to Make Black-Knight Fall in Love With Me!” has that exact situation, where a girl’s family is quite poor but the family name has enough cachet for her arranged marriage to a national hero.