I don't imagine anyone considers you are of an age to find parenting really difficult. It's not like you're 15. Perhaps you feel that being a teenage parent is what you categorise as young and because you're older than that you're not young. Young doesn't mean incapable and you shouldn't hear those saying you're young as saying you're incapable.
These things vary by area, social group, education etc. In many of these, early 20s will be pretty normal and for those becoming parents before 1980 early 20s was the usual age. It's stayed that way in some areas and groups, often those where people leave education younger and stay in the area they were brought up - big generalisation, but like all generalisations there s broad though not universal truth in them.
In some areas and groups things have changed radically in the course of a generation. Women being in education until their mid 20s and living with partners before marrying and having careers and facing delayed home ownership due to high costs in many areas - all of it has delayed the age many have their first child. Previously people were seen as freaks to have children at 40 as a first timer, but now it's very common and lots of people find that even by 40 they are struggling to have found a partner and financial stability.
20 years ago I was working in an ex-cloth trade town in w.yorkshire. I was a youth and children's worker in my very early 20s. Most of the mothers at the toddler groups I worked in were younger than me with their toddlers. By now, those toddlers have grown up and some will be parents themselves. At the same time, I have school friends who are in their early to mid 40s and there has been a surge of babies in the last 3 years. These babies are a whole generation older than those I saw 20 years ago. People are becoming grandparents and first time mothers who are the same age. The last 20 years of their lives have been very different.
I was 33 when I had my first. My Mum thought I was quite old. She'd been 26 and said she was considered quite old too. As it turned out, I was entirely average in my social group at the time and between about 32 and 35 loads of people had their first and most had another by about 36/37, with some having a third by 40. Those who had theirs beyond 40 either hadn't met their partner until later or had big careers and didn't really think seriously about it until late 30s or had fertility difficulties. Those in their 40s with babies and toddlers are physically tired but they have money to pay for help, are so keen to be parents and to do it well and love it.
At toddler groups, you often get a similar demographic but sometimes more of a range. Although mums can be a generation apart, sleepless nights, weaning aand nappies,plus choosing schools and managing tantrums face them all and bring them together, even if only for a short chat.