Of course not. You can't compare between sports. You can't compare Messi with Senna for example, or with Jordan or other greats, and say he is better than them.
Absolutely. As others have noted, we have immense difficulty in comparing footballers, golfers, tennis players, F1 drivers only separated by a few years (within their respective sports) How on earth can we compare Messi to Jordan to Jack Nicklaus to Karpov to Federer to Gretzky to Senna (or Schumacher) to Bubka to Bolt to Merck etc etc etc?
Hell, even comparing Federer, Nadal and Djokovic, three greats from the exact same sport, and of almost the exact same period is fraught with difficulties and pitfalls.
What I would say with absolute certainty though, is that Messi is far and away the best football player ever, with only Maradona roughly comparable.
BUT!
What you can say in favor of Leo, is that football is far and away the most popular sport on the planet (no other sport measures up to football's fingernail in terms of global presence) not just in the sense that it is followed by the greatest number of people, but in terms of the sheer number of professionals engaged with it. So, there you have it, Lionel Messi is the GOAT of the most universally competitive sport on the planet.