$400 2016 Specialized Allez. First Road Bike advice.

Good morning all. I’ll start with a little about me and what I’m looking for. Within the last two years I’ve really gotten into endurance training, focused almost entirely on running. I went from a guy who spent 20 minutes on a treadmill to running my first marathon back in April. I’m beginning to broaden my horizons and have a goal of completing a triathlon. I’m looking for my first road bike to start this journey. I have zero road bike knowledge. I’ve ridden bikes all my life but primarily just hybrids with no serious distance rides (longest ride I’ve done is about 25 miles). New bikes cost a lot of money and while I’m not opposed to spending money to get something new my gut is telling me to get something used first.

I found an ad for a 2016 specialized allez. Seller states the following:

“bicycle type: road
frame size: 54
wheel size: other/unknown
bicycle frame material: aluminum
Specialized Allez 54 cm road bike – aluminum frame-
used very rarely like new
including tire pump
500$
paid about 900 $
cash and carry do not message with any other requests of payments
if listed is available”

“It is 2016 still have receipt , comes with pump and helmet specialized. The bike is mine I am a female and bought a male road bike as
I am tall so that’s what they had at the moment and not quite a big difference anyway. But used probably 5 times, always sit-in in my bedroom then
I transfered it to the office.”

I offered $350 and she said she won’t go lower than $400.

My question: is this a good deal for an entry level bike that’s 8 years old? Would I be better off just making the investment on a brand new entry level bike such as a specialized allez or Giants Contend AR3?

As far as size goes I’m 5’8 175lbs so I think it should be a good fit.

appreciate any advice. Thanks.