Goodness, that’s quite a story! I’m so sorry you experienced this.
My reflection - it’s cultural and generational. While there are certainly aspects of being the eldest that are unavoidable, there are many variations in how we choose to parent. I remember being brokenhearted for my firstborn when I was close to my due date with my second. What she and I had shared was so special and it was all about to change. You have to strike a balance between accepting circumstances and going above and beyond to give the eldest the childhood they deserve. It’s simply conscious parenting.
Like with everything in life, there are blessings for every hardship. My eldest had the blessing of all of her parents’ love and attention and young energy - something both of her siblings missed out on. My youngest had to fit around his sisters’ busy after school schedules. But he gets prioritised over them at other times. And the gift of siblings is something I would never have wanted to deprive any of them of.
I know my eldest also loves being the experienced and responsible one. The first to do things and to then show her siblings the way. And she has a particular relationship with me that is different from the others’. I don’t think she would sacrifice that for anything.