Without automation, the day-to-day life of a full-service digital marketer probably looks a lot like someone who is spreading themselves too thin. While it is valiant to attempt to do everything yourself, it's easy to let things slip through the cracks if you aren't able to focus on one task at a time.
Having a store without having a website can be hard, especially when you're not selling your own goods. You risk quality problems, unexpectant shipping fees, and having more product than you can move. However, if you plan out your FBA business you've primed yourself for success.
The choice of hiring a digital marketing agency or a freelancer is one that is important to your business. However, a freelancer can provide the same online marketing results as an agency can, usually at a lower price.