As unsatisfying as it is to answer a question with another question, that is precisely what I am going to do: Why do we need to classify the economy in this time period as being called anything at all?

Sticking a label on an economy is a laborious exercise but hardly worth the trouble: we would need to first agree upon which characteristics define a "Capitalist" economy, and which characteristics define a "Feudal" economy. This is particularly difficult to do regarding "Feudalism," which is typically understood to be a political system and not an economic one. We would then, presumably, have to somehow assess if the "Capitalist" or "Feudal" characteristics are stronger or more present during the period in question in order to come up with an answer. But those characteristics were certainly not consistent across parts of Europe, and certainly are not at all consistent across the three hundred year period specified.

Even traditional Marxist narratives, which love sticking labels on things (although these labels reflect very specific Marxist definitions) typically admit that the emergence of capitalism and the capitalist economy was a gradual process, with roots as early as the thirteenth century.

It is important to keep in mind that most modern economics and economic labels only really make sense with regards to industrialized economies. So while in the year 1500 bankers in the Low Countries, Catalonia, and Northern Italy were dealing in complex financial instruments and enjoying returns on what we today would probably define as capital investments, it would be inaccurate to describe their activity as the primary driver of wealth and power in the societies they lived in. This is because prior to the industrial revolution, the European (and world) economy was predominantly agricultural.

But I cannot emphasize enough that this agricultural predominance exists on a spectrum. It's important to point out that agriculture and capital investment weren't mutually exclusive. Burghers could own and manage estates in addition to their commercial activity, while landowners could also invest in mercantile ventures. In many of Europe's most productive regions, very often there was no clear distinction between landholders and entrepreneurs. In a predominantly agricultural economy, land might even be said to be the most widespread form capital.

What even is Capitalism? If Capitalism is the mere existence of private enterprise, then we have to look no further than the collapse of the Mycenaean "Palace Economy" and trace the seafaring routes of ancient merchants as early as the Bronze and Iron age to find a "Capitalist Economy." If we define Capitalism the way Marx's did when he coined the term the way it is familiar to modern readers, a Capitalist society is one where there is a proletariat operating capital on behalf of capital's owners so that they may produce commodities in exchange for wages. While this wasn't the sole defining feature of Medieval Italy, it was certainly present at least since the existence of the Roman Empire (probably earlier, although the existence of a florid slave trade distorts labor dynamics in the pre-medieval economy). Some economies, like that in the Venetian Lagoon, would come to closely resemble this definition of "Capitalist" as early as the ninth century. But Marx's definition of Capitalism isn't even the only one used in Social Science: Schumpeter defines "Capitalism" as the presence of a credit market, and under this definition we can find even more examples of "Capitalist" economies in pre-modern Italy: In Florence, for example, the "Moneychanger's Guild" was founded as the first offshoot of the "Merchant's Guild" in 1202; so by this point in time, money lenders and money changers were already a well-organized presence within the Florentine economy.

But again, all we're doing is taking a nebulous notion which includes both politics and economics and trying to stick a date to it in order to find when it "Happened." It is much easier to look at simpler and less nuanced indicators, like when an economy transitioned from being predominantly agricultural to being predominantly industrial, and draw the appropriate conclusions, than it is to insist on finding a name for a certain system or try to apply a name originally used to define something else.