I've never had issues with the kids being mean or possessive but always "too lovey".
What worked for us sometimes was to tell them HOW they can interact with the baby and redirect. Showing them how to love the baby appropriately. Like...when the baby is sleeping (which is a lot in the beginning) you CAN hold her hand, smell her head or stinky feet etc. When she is awake you can kiss her on her head, you can tickle her feet, you can make silly faces and sounds at her.
There was a lot of "no you cannot jump around in her face but you CAN do this!" and a lot of "when she cries that means she wants to be left alone." Oh and also getting them involved with things like getting diapers, pulling out x number of wipes, getting socks, helping pick out outfits.
I think there are a lot of things our older sibs are figuring out, not just jealousy and wanting mommy to themselves but also that the baby has their own feelings and desires that are different from their own. Just because THEY want to tickle and love the baby doesn't mean the baby does KWIM?
Anyway, I also wanted to say not to be too hard on yourself either. You are full of mamabear instincts for your newborn and an older child climbing and jumping and being a child triggers every protective instinct you have. I think it's completely normal to feel irritated.
When you said you "failed last time" I think perhaps you are taking too much credit
My first 2 fight like cats and dogs, my 1st & 3rd are best buddies. I didn't do anything different. It's just personalities. I wonder how my 4th will fit in and how it will all play out.