I loathe all these bloody acronyms (lazy, and largely pointless) that have been spawned by the age of SMS, e-mail, and instant-messaging. I particularly loathe IMHO - it seems so unnecessary.
Of course this is an opinion. Of course it is MINE. Who else's would it be, for heaven's sake? It doesn't need to be tagged, highlighted - it can stand quite happily on its own. It certainly doesn't need to be apologised for, which is what that tag so often seems to be trying to do.
Are my opinions "humble"? Well, no, probably not.
I try to be humble in all the ways that matter: not considering myself more important than others, not making assumptions of entitlement, not selfishly trying to assert my needs and wishes ahead of those of others, "walking softly on the earth".
But are my opinions "humble"? NO. And I don't see any reason why they should be. A "humble" opinion is hesitant, feeble, ill-formed, half-arsed. I am robustly (but not, I hope objectionably) self-confident - particularly in regard to my intellectual abilities, my taste, my judgement. I stand by my opinions (and I have many of them!).
I do not suppose that I am always right. And I do not demand (often) that others agree with me. But I am not going to introduce my opinions in a fog of disclaimer, apology and self-doubt.
My attitude is always: THIS IS MY OPINION - Suck it and see!