Best way to invest long term as a young person working part time?

currently i am 15 years old and just got my first job 3 months ago, i make roughly 600-900$ a month and i'm currently investing 100% of that into VFV (s&p 500 ETF but processed in canada) my current net worth is around 6000$.

my question is that im curious if i should invest in anything else. People always say extra diversification even beyond the s&p 500 is good but to my research it seems like nothing really beats the s&p 500 consistently

please educate me, my goal is primarily build a good foundation for a long term investment portfolio