People tend to take normals less serious and frequently play champs they're not very good at there, while people in ranked usually will only play their best champs and will take it pretty seriously, which makes 'silver' mmr in normals (as in the mmr where you're matched against people who are silver in ranked) much lower than silver mmr in ranked. I'd probably say the mmr where you get matched mostly with silvers in normals is probably bronze-ish in ranked (i.e. a silver player not trying very hard with a champ they don't know is probably as good as a bronze player trying their hardest on their main), so the normals mmr where you find yourself matched with silver-gold border folks would probably be around low silver ranked mmr.
There not an in between queue, so the options are to play your main(s) in normals until you get up to a gold mmr or whenever it actually gets difficult for you, or to bite the bullet and learn via ranked play. It might feel bad to see yourself fall in ranks initially if you feel like you're better (e.g. because you see shinier borders and still do well when playing normals), but people in ranked really will try to punish your mistakes much more so than in normals, and ranked really is a better test of your skills than normals for that reason.
The upside is after the initial fall, you'll basically be at the optimal level of opponent difficulty to practice and get better, so spamming ranked does double duty as the best place to practice, and also where you get rewarded for your practice as you climb through the ranks for increasingly shiny borders.
