There isn't a single Way to the Top, because The Top looks different for different people. For more on that, I'd recommend:
So try to develop all-around competency, but figure out what draws you. Maybe it's writing awesome application code. Maybe it's visual aesthetics for web and mobile apps. Maybe it's Ops. Maybe it's algorithms and/or machine learning. Maybe it's dealing with people and being a leader. (Industry secret: Many managers, even with programming backgrounds, are less skilled programmers than most of their subordinates, and that's not actually a problem!)
You need a little bit of everything (though there are exceptions, e.g. you can probably skip machine learning if you're focused on line-of-business web apps, and there are probably almost no cases where knowledge of both writing mobile apps and hardware hacking is necessary), so look for opportunities to round out your experience. Over time, you will hopefully find a specialization where you can really shine. It's kind of like college in the US (i.e. not European) model - take some general courses and then declare a major. It's OK not to have a major yet when you're new. It's also totally OK to like lots of things as you move along, and go back and forth flexing different muscles as you progress. (As an example, see Charity Majors' essay on bouncing between engineering and management positions.)
Finally, if anyone RTFMs you or references you to Eric S. Raymond's essay on how to ask smart questions, RUN and don't look back. As a junior, you need an environment where you feel safe asking questions, knowing you'll be respected for doing so. That difference can shave years off the time it takes to graduate from junior to mid.
Oh, and when you do move into a more senior role, remember how hard it is to be junior, and find ways to mentor/pair/be available/encourage questions DURING work hours.
P.S. If you're interested in public speaking, you don't need to be an industry expert. Most speakers aren't, they just (ideally) know how to research and craft data into a good story! You really can become a prolific meetup/conference speaker much earlier in your career than you'd think!
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