Is digital marketing considered an IT job? Definitely not, and far from it.

This is equivalent to calling a doctor that helps people online an “IT guy”.

Marketing aims to eliminate the need of having a sales team.

Digital marketing is like having 1000s of salespeople without the cost (especially in product-based businesses)
IT is for operations (including everything backend, security, maintenance, development), and fulfilment of work orders
To even consider taking on marketing, you’d need to learn about:

Sales psychology
Market research and positioning
Direct response copywriting
Psychological design, and user journeys
Email marketing and so much more