This is what Lord Krishna says in Uddhava Gita
A saintly person should step or place his foot on the ground only
after verifying with his eyes that there are no living creatures, such
as insects, who ...
Hinduism says that it is impossible to avoid killing insects.
Tuladhara said, ‘People regard the profession of agriculture to be
sinless. That profession, however, is certainly frought with cruelty.
The below verses are self explanatory.
That old man Ajāmila had ten sons, of whom the youngest was a baby
named Nārāyaṇa. Since Nārāyaṇa was the youngest of all the sons, he
was naturally very dear ...
The ancestors roam around in the form of crows. Or another way to put it is ancestors come in the disguise of crows to accept the offerings.
Quoting from Baudhayana Dharmasutras Praśna II, Adhyāya 8, ...