This isn't going to be a super lengthy reply but the answer to this can be summed up essentially as "definitions are shaky, but also heavy".

In literature the terms "heavy cavalry" and "shock cavalry" get used interchangeably and the distinction between light cavalry tends to fall under "Wears lots of armor. Does heavy cavalry things" which is as much technical as doctrinal. In the period we're discussing, plenty of cavalrymen wore armor, if just a cuirass and a helmet, and still did light cavalry or dragoon things. You do generally start pushing technical definitions for "heavy" when we're talking more a a suit or harness depending on the book you're reading like a cuirassier or what all and, yes, a hussar. That's technical, it's flexible, what's more objective would be a doctrinal difference.

In the case of these Hussars, they were generally armored lancers who performed as such. Many hussars would also serve other roles suitable to the warrior noble class that they were in the Commonwealth. In battle and in campaign, their roles were pretty wide ranging but, yes, a big part of them was as you say "shock attacks". Generally this just takes the form of immediate and repeated charges with lances, a pretty typical thing you see with all kinds of heavy/shock cavalry, especially lancers like themselves. The specifics of this get a bit murky but also it's beyond the scope of your question so I'll leave it at that for now. Now beyond this, your question does hit on an interesting question in that the Hussars were at least slightly queer for the time and did not share entirely with heavy cavalry in western europe. This is a massive topic by itself but in brief, this is at least in part related to the people they were facing and the relative geography of where they were fighting as well as how the Poles approached warfighting. These hussars were, as you observe, fast, they primarily mounted swift horses bred for bursts of speed and tended to be unarmored or minimally armored. They were made to immediately and decisively wipe out or see off groups of infantry, especially pikemen. Much of how they were outfitted is in keeping with this and while we definitely must look at them as at least a bit distinct relative to other heavy cavalrymen in europe at the time (and without making this answer the length of a dissertation) we may still look at them under the umbrella term of "heavy cavalry" though that term is, sometimes, a little meaningless. Without getting too weapon/armor focused, the details of their kit and of their behavior in the field is that of heavy or shock cavalry, yes.

Mind you they weren't the only heavy lancer types in Europe at the time or even in the commonwealth, there were various groups in the Caucasus, within Cossack groups, and even to some degree in Muscovy that operated in a similar fashion (there was a particularly amusing period after the war with Poland where some people in Moscow raised/attempted to raise some units of their own hussars modelled after the Commonwealth hussars.), some even as Polish mercenaries in Muscovy as was the case with Lisowski who also organized his men in a similar fashion.

There were, of course, other types of hussars in the world later on, though as far as the Commonwealth goes, not at the same time. Generally the term "hussar" gets applied to light cavalrymen as adept with a horse and saber as with a glass of wine and a woman of dubious employment that you see in the eighteenth, nineteenth, and to a very limited degree, the twentieth centuries. These dudes were dedicated light cavalrymen that did light cavalrymen things, they also were not the winged hussars and vice versa, this was a later development and they didn't really exist concurrently. Though at the same time, the Poles also maintained lancers well into this same period, as did others. They very famously fielded many regiments of lancers during their tenure in the Grand Army and armies in Europe maintained their use going forward.

It is worth noting that these lancers were generally light cavalrymen, though there was some experimentation with arming the first rank of a cuirassier formation with lances (note, these are not analogous to cuirassiers of the sixteenth and seventeenth centuries, these individuals tended to just wear a cuirass and helmet), some others with hussars in a likewise manner, but ultimately there wasn't much left of the sixteenth and seventeenth century hussars. I'll also state that the lances they used were much shorter and lighter than the lances seen in the hands of the winged hussars, there's a lot of reasons for this, again, beyond the scope of the question, they also had debatable lethality if we're to refer back to Nolan, but well.

Anyway, I've branched out quite far from the scope of your question, so to bring it all back, yes, the hussars of the Polish-Lithuanian Commonwealth in the sixteenth, seventeenth, and beginning of the eighteenth centuries were heavy cavalrymen or shock cavalrymen. The way they outfitted themselves and the manner in which they operated were all in keeping with this. When we say "shock" we don't necessarily mean "surprise" or "ambush" as much as the functional result of the attack. There were other types of hussars, though not in this period, and they were light cavalrymen, though this didn't necessarily mean that lances died out as much as they were modulated along with the role of lancers to varying degrees of success.

This isn't my best answer but I decided to take a stab at it, primarily drawing from the following material:

Lisowski's Free Lances: Polish-Lithuanian Mercenaries in Muscovy's Time of Troubles by Davies, it's a brief paper but it provides a decent overview of the title subject as well as some details on the kit and structure of forces that were modelled and represented in this particular group.

The Northern Wars: War, State and Society in Northeastern Europe, 1558–1721 by Robert Frost. This is the one I've primarily taken from, he has an excellent single volume breakdown of perhaps one of the most tumultuous and criminally underdiscussed eras in Eastern and Northern European History. I will state that I do not fully agree with Frost's assessment of Hussars as of the mid-sixteenth century, but then, his professional opinion is still completely valid and I've learned a lot from him as well as from people that he vehemently disagrees with such as Parker. All in all, great book on the topic even if I have some qualms with some of his editorial comments.

After the Deluge: Poland-Lithuania and the Second Northern War 1655-1660 also by Robert Frost. I largely took aspects of social and political makeup from this book as well as some aspects of just how Cossacks and the nobility figured into the military at this time. A very interesting read on the whole and a good companion to his The Northern Wars and any reading list about the "Deluge".

The Campaigns of Napoleon by Chandler. This one is old and in some ways outdated though it's not as if anyone else is stepping up to try and take its place so for the time being it remains the sole one-volume look at the military and political undertakings of the French Empire and its little corporal. I largely used this for information regarding light and medium cavalry in the late eighteenth and early nineteenth centuries, especially those of lancers as it was relevant for this question.

And finally, the various publications of the tragic artillery victim Captain Louis Edward Nolan. Nolan was particularly critical of lancers from a lethality standpoint though he personally contended that, in a similar light as bayonets, they tended to inspire fear in those facing them and so served something of a role as far as seeing off enemy cavalrymen if not directly killing them. I'm not bringing Nolan up because I fully agree with him as much as because this was a contemporary opinion on the matter of lances and lancers as they existed and developed in the mid-nineteenth century.