Wikipedia defines an entrepreneur as:
An individual who organizes and operates a business or businesses, taking on financial risk to do so.
Wikipedia then goes on to provide prominent variations of the definition by various scholars over time. Personally, I like W.B. Gartner's 1985 definition:
Entrepreneur is a person who started a new business where there was none before.
So, to answer your question
Are business owners (ecommerce) considered entrepreneurs too?
It depends on your definition of "business owner."
A business owner who starts a business from scratch is an entrepreneur. These people are usually referred to as founders.
On the other hand, someone who owns part of a business, but does not go through the process of building the business from the ground up is not an entrepreneur. An example of someone that could fall under that category is an investor. An investor may give an entrepreneur money in exchange for a percentage ownership of the company. Therefore the investor is part owner, but that does not neccesarily make him an entrepreneur.
The industry the company is in doesn't matter in defining an entrepreneur. So whether it is ecommerce, manufacturing, or a restaurant it doesn't matter.
As to why incubators seem to only be interested in technology startups, that's their prerogative. Tech startups are easier to start and build, and usually require less upfront cash to get started. It is also something a lot of people have domain knowledge in, so they can actually help entrepreneurs. However, there are incubators that focus on other industries.