The group of verbs which would normally take the present tense of the verb to be plus the present participle as the normal present tense tend to be verbs of action, which could all be answers to the question "what are you doing ? "

nobody would answer "I garden " or "I weed" or "I paint my house" in response to the question.

These verbs which customarily take this form in the present tense differ from verbs which express a more cerebral or emotional state, such as "I love", "I hate", "I detest", "I fear", "I distrust" which sound strange when expressed as "I am ... + present participle".

Maybe you hadn't noticed, Alex ...