Nope, those of the original syllabus are stylized versions of older variants ie from bushi Matsumura.
Let's turn it on its head. What evidence is there that the Shorin forms are older?
The Matsumura Sieto Shorin ryu traces directly through Matsumura's family, yet some of their kata are closer to Funakoshi's, especially chinto which Shotokan folk get a lot of stick about due to their versions relative simplicity. Matsumura Sieto have no cat stance which many fixate on as being somehow older than back stance. They use a horse stance with the knees pressed outwards like Funakoshi, while Itosu was said to have turned his toes inwards.
These differences in Itosu's style compared to Matsumura's were pointed out by Motobu. Matsumura thought Itosu a crap student and didn't teach him much. His next teacher from naha-te only taught him strength work. He learned his karate from Oyadomari of Tomari.
The fact is that GF was older than nearly all the rest and trained under a different lineage than most (ie under Azato while most other Shorin descends from Itosu). This is why his kata look different.
In the 30's Funakoshi said how karate had changed dramatically. We know that Itosu liked to create kata. In fact it's the Okinawan way that every new master puts his personal stamp on his kata with his own adjustments. So it's unlikely that no more change happened after 1925 when we have the earliest records of pinan kata and others through GFs books. Hell GF was nearly dead when Matsubayashi ryu was founded.
Because of the Shuhari principle every line of instruction produces slightly different kata. There's nothing wrong with them. Fixation on "older" is a modern thing. But if we want to find older we need to look at the shortest lines, the fewest masters to leave a stamp on the kata.
Matsumura - Azato - Funakoshi. That's about as short as it gets.
Gichin Funakoshi learned his karate in the 1800s and that is what he passed on.
I think when you leave the bias (from years of hearing how crap and un Okinawan Shotokan is) behind you'll realise that the evidence is actually pointing a different direction to the one you thought.