When "much" is used as an adverb, can it be used to modify a verb? Does "We all love him much" make sense to you, native speakers?
Yes, the word much can be used as an adverb.
As per Technic Empire's comments, you should say "We all love him very much". You use very with much in positive sentences. However, you can use much without very in negative sentences. Please look at the following examples of the use of much as an adverb modifying verbs.
He didn't help much.
Thank you very much for the help.
I would very much like to go with you.
I didn't enjoy it much.
I enjoyed it very much.