For a strong student with a strong GPA in fairly rigorous courses, if they have almost no extracurricular participation (without any real excuse other than that they weren’t interested in any extracurriculars and/or just didn’t feel like they fit in socially with the other students insofar as the culture at their high school and therefore didn’t feel like they would enjoy any of the extracurricular clubs, teams, etc.) until late in the second half of their high school sophomore year, what are the ramifications? If they become active in some significant extracurriculars beginning in the second half of high school sophomore year and continuing through the remainder of high school, will they still be a much less competitive applicant than their peers who were active in many extracurriculars ever since the beginning of high school? Also, with the “late start” in the extracurriculars, considering that it will make it less likely to rise to a leadership position in any of the extracurriculars, how much of a disadvantage in the college application competition will this put the student? I’m talking about a highly academically able student that, academically, if it were possible to gain admission, would want to go to a highly competitive LAC or an ivy…Does this student still have time to make up for the “slow start” extracurricular-wise, insofar as how they can present for college admissions?
You did NOTHING your first year and a half of HS? No jobs? No outside activities? ECs are not just at school.
What’s done is done. Just work to become an involved member and perhaps by senior year you will be able to make significant contributions and/or obtain some leadership positions. You can also get involved in things outside of school.
Did one fall sport in fall of freshman year and fall of sophomore year (and plan to continue that each fall) ; a sport that was just getting learned for the first time, so only at JV level and unlikely to catch up to the others (who have been playing it and getting lessons in it since early childhood) enough to reach a leadership position . But other than that; yes, nothing else. No jobs or other outside activities. Basically watched a lot of tv and surfed the internet 
Can the presentation to colleges be salvaged by getting a move-on and joining/participating a lot going forward?
You can’t focus on the past- instead, focus on now finding activities you are passionate about, whether those are in or out of school. You could try volunteering or getting a job.