There are two different paths.
First, if you can get 5 people to play together, win premier (which is highly unlikely considering the cheating that goes on in premier), then some how get to ascension, win ascension, your team becomes pro if it doesn't get absolutely picked apart prior to getting to VCT.
Second, you play in Mr Funhaver tournaments, you get recruited into a tier 2 team, you attend a LAN or two, you personally do extremely well and place high or do well but your team consistently places top 3, you play for a long period of time, you get a tryout for a VCT team, do well in the tryout.
Each of these paths require EXTENSIVE networking with people and being the world's largest kiss ass unless you're a godly player winning LANs by yourself.
In 2027, there will be a BONUS path. That will be similar to the second path but since there will be cups, you have more opportunities now to show up at an Riot official cup or tournaments.
The only way ranked helps you, is if you network while playing ranked, befriend every good player you run into and become their best friend. To give you credit, you sort of identified this in your post.