First let’s start with busting a myth:
Esperanto is not meant to replace natural languages.
Esperanto is the world’s most widely spoken constructed language.
The idea behind Esperanto is that everyone should learn it as their second
language. Then, when two people who don’t share another language want to communicate, they can use Esperanto.
Moreover, they will be on relatively equal footing since the odds are neither of them are a native Esperanto speaker.
(There actually are native Esperanto speakers. According to Wikipedia, there were about 350 in 1996. You can hear some of them on YouTube: Esperanto: Like a Native)
To this end, Esperanto is designed to be easier to learn than natural languages. There are studies that show that it really is, and that learning Esperanto first can help when learning additional languages.
Esperanto isn’t perfect, but finding consensus on perfect is much harder than finding consensus on “good enough”. Esperanto’s creator himself created an improved version, but it couldn’t gain the traction that Esperanto had. Among constructed international auxiliary languages, Esperanto has been most successful.
I think English speakers in particular should support Esperanto as the world’s international language. While English seems to be the current lingua franca, it wasn’t the first. (As “lingua franca” itself attests.) It won’t always be. You can be guaranteed that if the next one isn’t Esperanto, it is going to be harder for you to learn than Esperanto.
If you’re interested in Esperanto, here are some starting points I recommend:
Of course, there is much more, but those are places to start.
†The web version of the Duolingo Esperanto course includes some helpful grammar notes that are missing from the app. In any case, while I find Duolingo very helpful, I find it isn’t enough by itself to learn a language.