If I create a site and do not built any of the backlinks would it get crawled by Google?
Off page SEO is not required
Google does not base indexation based on off page SEO but rather than discovery, Google has many ways of discovering new sites such as: Sitemap Submission to Google and can even find new registrations of domains via the name servers they use.
Many old domains will already have back links and even if you register a new domain your domain name will appear over the internet in a newly registered domain list such as this one.
Sitemaps are not needed for indexing
Many people believe that Google requires a sitemap for the site to be crawled and indexed, this is far from the truth.. You don't need a sitemap at all, some people believe it makes Google crawl the page quicker, in effect it can but its all done on a queue system, often a back link can trigger a crawl quicker than a sitemap submission.
Other sites that back link without you knowing
There are many other websites that will crawl your site and collect data, and list statistics on their website such as page rank, alexa rank, and so on... These sites are very common and they back link. Again, they don't always use Google to find your site and many other methods can be used.
I'm not completely sure why your asking this question, maybe its out of pure interest if that's the case then ignore this part, if you want to stop Google crawling your site period then us noindex paired with a robots.txt denied.
There is one way for Google to know your site exists without any back links and that is to submit them a sitemap. You do this by registering for Google Webmaster Tools which lets you supply a text of XML sitemap for your site. The sitemap does not even have to be complete since Google crawls URLs from there.
Without any back-links, built by you or anyone else, there is little chance to rank for common words in most languages because so many other sites will do better. However, if you have something unique, be it your own name or an invented name for a product, Google will list your site for relevant queries.